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United States Patent |
6,206,563
|
Dombre
,   et al.
|
March 27, 2001
|
Device for leakproof fastening of a watch glass to a watch case
Abstract
A device comprising an annular seal having an annular projection engaged
into a groove in the edge of the watch glass is disclosed. The lower part
of the seal, said lower part having a bulge, engages onto a surface of the
housing and is compressed radially by the bezel. The inner lateral surface
of the bezel, said surface being fitted around this seal, comprises two
concentric cylindrical surfaces of different cross sections, the surface
of larger cross section being that which is adjacent to the base of the
bezel, these cross sections being slightly smaller than the cross sections
of the outer lateral face of the seal and of the bulge in the
non-compressed state. The base of the outer lateral surface of the upper
part of the housing has a groove in order to receive a portion of the
seal, said portion being deformed by the bezel, thus ensuring the axial
blocking of this seal.
Inventors:
|
Dombre; Christian (Annemasse, FR);
Passaquin; William (Thonon-les-Bains, FR)
|
Assignee:
|
Montres Rolex S.A. (Geneva, CH)
|
Appl. No.:
|
515904 |
Filed:
|
February 29, 2000 |
Foreign Application Priority Data
| Mar 03, 1999[EP] | 99810182 |
| Mar 26, 1999[EP] | 99810263 |
Current U.S. Class: |
368/294 |
Intern'l Class: |
G04B 37//00; .39/00 |
Field of Search: |
368/88,276,291,294-296
|
References Cited
U.S. Patent Documents
2854815 | Oct., 1958 | Piquerez.
| |
4456388 | Jun., 1984 | Matsumoto | 468/294.
|
4668101 | May., 1987 | Wuthrich.
| |
Foreign Patent Documents |
583 438 | Dec., 1976 | CH.
| |
653 844 | Jan., 1986 | CH.
| |
28 17 770 | Nov., 1978 | DE.
| |
Other References
Patent Abstracts of Japan, vol. 006, No. 129 (P-128), Jul. 15, 1982, and JP
57 054883 A (Seiko Epson Corp), Apr. 1, 1982 *abrege*.
|
Primary Examiner: Miska; Vit
Attorney, Agent or Firm: Henderson & Sturm LLP
Claims
What is claimed is:
1. A device for the leakproof fastening of a watch glass to a watch
housing, comprising an annular seal of a cylindrical general shape, said
annular seal consisting of a compressible material having an inner annular
projection at the upper end of said annular projection at the upper end of
said annular seal, an annular groove positioned on an edge of the watch
glass into which said annular projection is engaged, an outer lateral
surface made on the upper part of the housing in order to receive the
lower part of the inner face of said annular seal, the base of which comes
into abutment against a bearing surface of the housing, and bezel fitted
around said seal, at the same time compressing the latter radially,
wherein the base of said annular seal has an annular bulge projecting at
least from its outer lateral face, and wherein the inner lateral surface
of the bezel fitted around this seal comprises two concentric cylindrical
surfaces of different cross sections, the cylindrical surface of larger
cross section being adjacent to the base of the bezel, these cross
sections being slightly smaller than the cross sections of the outer
lateral face of said annular seal and of said annular bulge in the
non-compressed state, the base of said outer lateral surface of the upper
part of the housing having an annular groove in order to receive a portion
of said annular seal, said portion being deformed as a result of the
fitting of the bezel, thereby ensuring the axial blocking of this annular
seal.
2. The device according to claim 1, wherein said annular bulge projects on
either side of the inner and outer cylindrical faces of said annular seal.
3. The device according to claim 1, wherein the injection points of said
annular seal are located on its outer cylindrical face between said
annular bulge and the part where the inside diameter of the bezel becomes
smaller.
4. The device according to claim 1, wherein said annular seal consists of a
polymedic material, the modulus of elasticity of which is between 1000 Mpa
and 3000 Mpa.
5. The device according to claim 2, wherein the injection points of said
annular seal are located on its outer cylindrical face between said
annular bulge and the part where the inside diameter of the bezel becomes
smaller.
6. The device according to claim 2, wherein said annular seal consists of a
polymedic material, the modulus of elasticity of which is between 1000 Mpa
and 3000 Mpa.
7. The device according to claim 3, wherein said annular seal consists of a
polymedic material, the modulus of elasticity of which is between 1000 Mpa
and 3000 Mpa.
Description
FIELD OF THE INVENTION
The present invention relates to a device for the leakproof fastening of a
watch glass to a watch case, comprising an annular seal of cylindrical
general shape, made of a compressible material and having an inner annular
projection at the upper end of this annular seal, an annular groove made
on that edge of the watch glass into which this annular projection is
engaged, an outer lateral surface made on the upper part of the housing in
order to receive the lower part of the inner face of said annular seal,
the base of which comes into abutment against a bearing surface, and a
bezel fitted around said seal, at the same time compressing the latter
radially.
Devices are already known for the leakproof fastening of a glass consisting
of hard material, such as toughened glass or sapphire, in which the glass
consisting of hard material is fastened in a ring produced from a material
which is soft in relation to the watch glass and also in relation to the
metal of the case to which it is to be fastened. This ring usually
consists of organic glass, such as Plexiglass.
DESCRIPTION OF THE PRIOR ART
A fastening device of this type is described in CH 519 193, in which the
watch glass is accommodated in a ring consisting of organic glass, the
entire assembly subsequently being introduced by mounting into a
receptacle of a bezel housing, the deformations resulting from the
mounting operation being absorbed by the ring consisting of organic glass
which also ensures the leakproofing of the fastening. A false bezel may be
fastened to the bezel housing in order to conceal the fastening ring of
the watch glass. In a variant, the fastening ring is accommodated in an
annular groove made in the edge of the watch glass, so as not to project
from the periphery of the latter and thus not be visible.
Such a fastening device is necessary for the annular seal surrounding the
watch glass to be subjected to stress before this assembly is fastened in
an orifice of the housing. The removal of this assembly presents serious
problems, since the prestressed seal is entirely embedded in the housing
and the glass of sapphire or toughened-glass type cannot be deformed.
CH 583 438 proposed a solution which does not have the abovementioned
disadvantages and in which the annular seal made of relatively soft glass,
which surrounds the watch glass, is engaged around a lateral surface made
on the upper end of the housing, around the raised portion, and is
compressed radially against this lateral surface by the bezel mounted
around this seal. In a preferred embodiment, not described in this patent,
the bezel extends over the entire height of the annular seal, so that the
upper part of this seal is compressed between the bezel and the watch
glass and so that the lower part of this seal is compressed between this
bezel and the lateral surface of the housing on which it is engaged.
Although this fastening method has proved successful for many years,
particularly with regards leakproofing, it became clear that its design
was capable of being improved even further in many respects.
Thus, in the abovementioned fastening system, only the frictional force
makes it possible to ensure that the annular seal is fastened to the
lateral surface of the housing, so that the seal must have sufficient
rigidity, giving rise to pronounced stresses on the other parts,
particularly giving rise to a torque tending to deform the raised portion
and the bezel.
The same surface of the bezel serves for clamping the seal around the watch
glass and around the lateral surface of the housing. In view of the many
manufacturing tolerances in the various elements involved in this
fastening, the force necessary for removing the bezel may vary in a ratio
of 1 to 4. In view of the differences in the frictional forces occurring
as a result of these tolerance variations, the position of the bezel after
mounting may change slightly from one piece to another, thus having
effects on the compression of the annular seal.
During the mounting of the bezel, the seal undergoes deformations in the
region of the watch glass which are greater than those determined by
leakproofing. If this seal is clamped firmly, there is a risk that it will
form a bead which is interposed between the housing and the bezel and
prevents the latter from being laid against the housing. It is also
possible, in the event of a sharp compression of the annular seal, that
the latter is deformed into the space provided between the watch glass and
the housing.
As a consequence of the design of the assembly operation, in which, in the
assembled position, the bezel is held solely by friction around a piece
consisting of compressible material, the bezel remains subject to a force
tending to cause it to rise.
Finally, the injection points can be located only in a visible zone or in a
contact zone and are therefore annoying in both cases.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is partly to overcome the
abovementioned disadvantages.
To achieve this, the subject of this invention is a device for the
leakproof fastening of a watch glass to a watch case according to claim 1.
One of the essential advantages of the present invention is due to the fact
that the base of the annular seal is retained on the housing by anchoring
and no longer by friction. Consequently, the extreme values of the force
necessary for removing the bezel come within a somewhat limited range, in
spite of the disparity of the clamping values inherent in the
manufacturing tolerances of the various elements.
Another great advantage is due to the fact that the annular seal is no
longer radially compressed uniformly over its entire height, but that two
separate compression zones are formed, one in the region of the watch
glass and the other in the region of the fitting surface, adjacent to the
upper edge of the housing. Thus, during the mounting of the bezel, its
base does not compress the upper part of the seal, thus avoiding the risk
of formation of a bead which comes into place between the bezel and the
housing.
That part of the annular seal which is located between the lower face of
the watch glass and the upper edge of the housing is not compressed, or
compressed very little, radially, thus avoiding the risk of being deformed
into the free space separating the watch glass from the housing. The
radial compressions induced in the two clamping zones are not necessarily
the same, but may be adapted to requirements independently in each zone.
Since the hold of the assembled elements is not attributable solely to the
frictional forces, it is then possible to use a seal consisting of a less
rigid material, thus making it possible to reduce the stresses exerted on
the other elements and, in particular, on the raised portion.
Contrary to the seal of the fastening device of the prior art, in the
present invention, when the seal is injected, the injection points of the
seal may be arranged, particularly with regard to opaque seals, in that
portion of its outer face which is located between the bulge of the base
of the seal and the part of smallest diameter of the inner face of the
bezel. After mounting, this portion is, in fact, concealed by the bezel
and also forms a non-functional zone of the seal, since said portion is
not in contact with any surface of the bezel.
It can be seen that, by preserving the same general principle for the
leakproof fastening of the watch glass as that known from the prior art,
the present invention makes it possible to afford substantial improvements
which are appreciable, in particular, during the assembly operations and
also in terms of maintenance, since demounting is thereby made easier by a
narrower dispersion of the values of the forces for removing the bezel,
without any impairment in leakproofing efficiency, on the contrary.
BRIEF DESCRIPTION OF THE DRAWING
The invention will be understood more clearly from a reading of the
following description relating to an embodiment and a variant of the
device for the leakproof fastening of a watch glass, which is the subject
of this invention, and with the aid of the accompanying drawings in which:
FIGS. 1 to 4 are partial views in diametral section, illustrating four
steps in the fastening of a watch glass according to this embodiment,
FIG. 5 is a view in diametral section, similar to that of FIG. 4, of a
variant.
DETAILED DESCRIPTION OF THE INVENTION
In the embodiment illustrated in FIGS. 1 to 4, there can be seen a watch
glass 1, an annular seal 2 of cylindrical general shape, the upper part of
a housing 3 and a bezel 4 mounted around the outer face of the annular
seal 2. This watch glass, which preferably consists of a hard material,
such as toughened glass and, more advantageously, sapphire glass, is
machined from a sheet. The edge of the watch glass 1 is delimited by two
portions of different diameters, one of large diameter 1a and the other of
smaller diameter 1b, adjacent to the lower face of the watch glass 1. An
annular groove 1c separates these two portions 1a and 1b.
The annular seal 2 has an inner annular projection 2a adjacent to its upper
edge. This projection 2a penetrates into the annular groove 1c of the
watch glass 1, whilst the portion of small diameter 1b penetrates slightly
into the inner face of the annular seal 2. To make understanding easier,
in all the figures the deformed portions of the annular seal 2 have been
illustrated in their non-deformed state by broken lines.
The lower part of this annular seal 2 is engaged around a lateral
interlocking surface 3a made at the upper end of the housing 3 and located
substantially at the same level as the raised portion 3b. The base of this
lateral interlocking surface 3a has an annular groove 3c.
A swollen heal 2b projects symmetrically on either side of the inner and
outer lateral faces at the base of the annular seal 2. That part of this
swollen heal 2b which projects on the inside of the annular seal 2 engages
into the annular groove 3c of the lateral interlocking face 3a.
The inner lateral face of the bezel 4 comprises two cylindrical portions, a
lower portion 4b of larger diameter and an upper portion 4a of smaller
diameter. The diameter of the lower portion 4b of larger diameter of the
inner lateral face of the bezel is greater than the diameter of the outer
lateral face of the annular seal 2, but smaller than the outside diameter
of its swollen heal 2b, whereas the diameter of the upper portion 4a is
smaller than the diameter of the outer lateral face of the annular seal 2.
Thus, during the mounting of the bezel 4, the lower portion 4b of the bezel
engages freely around the annular seal, since the diameter of this lower
portion is larger than that of the annular seal 2. Only when this lower
portion 4b comes level with the swollen heal 2b does it compress the
latter in the annular groove 3c of the lateral face 3a of the housing 3,
thus fastening this seal 2 to the latter.
Simultaneously with the compression of the swollen heal 2b by the lower
portion 4b of the bezel 4, its upper portion 4a, having a smaller diameter
than the seal 2, compresses the upper part of the latter, that is to say
essentially that part which is located in the region of the watch glass 1,
at the same time pressing the inner annular projection 2a of the seal 2
into the annular groove 1c of the watch glass 1 and also causing that part
of small diameter 1b of the watch glass 1, said part being located below
the inner annular projection 2a, to penetrate slightly into the seal 2.
It can be seen that, with this device, the fastening of the seal 2 is
assured at its two ends, on the one hand, by the penetration of the inner
annular projection 2a into the annular groove 1c of the watch glass 1 and,
on the other hand, by penetration of a portion of the swollen heal 2b of
this seal 2 into the annular groove 3c of the housing. In both cases, this
engagement of the seal into the annular grooves 1c and 3c is accompanied
by the centripetal radial pressure exerted on the annular seal 2 by the
bezel 4. This seal is therefore no longer held on the housing simply by
friction, but by hooking. This fastening method thus makes it possible to
use a softer material than in the abovementioned prior art. Whereas the
seal has hitherto been produced from 6.6 polyamide, the modulus of
elasticity of which is between 2100 and 3000 MPa, in the present invention
it may consist of polyamide, in particular PBT or POM, the modulus of
elasticity of which is between 1000 and 3000 MPa.
The variant illustrated in FIG. 5 differs from the embodiment described
above only in the shape of the annular seal 2' and, more specifically, in
the shape of the swollen heal 2'b. Contrary to the swollen heal 2b, the
latter projects only on the outer lateral face of the annular seal 2',
leaving the inner lateral face of this cylindrical annular seal 2'
downward from the base of the inner annular projection 2'a engaged into
the annular groove 1c of the watch glass 1. The hooking of the annular
seal 2' in the annular groove 3c of the housing 3 occurs as a result of
the deformation of the base of this annular seal 2', said deformation
being induced when the lower part of the bezel 4b engages onto that part
of the swollen heal projecting on the outer lateral face of the seal and
imparts centripetal radial compression to said part.
This variant has the advantage of making it easier to remove the annular
seal 2' from the mold during its injection, while at the same time
preserving the system of anchoring this seal on the housing. This variant
also allows the mounting and demounting of the annular seal 2' to be made
easier.
As can be seen, the changes made to the fastening device of the prior art
give rise to virtually no complication either as regards the operations of
machinery or injecting the various elements or as regards the mounting
operations, so that the great advantages which have been seen are
obtained, without entailing any disadvantage and without the need for an
additional operation either in the manufacturing program or in the
mounting operations.
Advantageously, the injection points of the seal 2 or 2' will be located
opposite that part 4b of the bezel 4 which has the largest inside diameter
and on the outer face of the annular seal 2 or 2', said outer face being
located between the heal 2b or 2'b and the top of the part 4b of the bezel
4. Thus, these injection points are not visible and are not located in a
contact zone of the annular seal 2 or 2'.
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